There are shoes that are impermeable in the region of the upper, for example as a result of lining the outer material of the upper with a waterproof layer. This is preferably a waterproof, water-vapour-permeable functional layer, by means of which waterproofness is achieved while maintaining breathability, i.e. water-vapour permeability. The functional layer is often part of a functional layer laminate that has in addition to the functional layer at least one textile layer.
Shoes of this type are either equipped with a functional layer in the form of a so-called bootee, which lines the entire interior of the shoe, or only the upper is lined with a functional layer. In the latter case, special efforts are required to ensure permanent waterproofness in the region between the end of the upper on the sole side and the sole construction.
In shoes which are produced by the known cement-lasting process, the upper of the shoe is cemented to the underside of the insole along a border region, which is referred to as the lasting allowance, and an outsole is applied to the underside of this cemented unit. This construction has weak points. Weak points are, in particular, points at which the contour of the shoe has a small radius of curvature and folds of the lasted upper material occur in the lasting allowance, because the lasting cement either does not seal the entire transitional region between the upper of the shoe and the insole from the outset, in particular in the region of the lasting folds, or becomes brittle and consequently water-permeable as a result of flexural stresses during use of the shoe.
It is known from DE 40 00 156 A to arrange reactivatable sealing cement, which may be silicone or polyurethane, between the periphery of the insole and the functional layer of the upper. To prevent water which reaches the underside of the insole via the outer material of the upper and the lasting allowance from being able to get into the space inside the shoe, the insole is provided with a waterproof insole layer. There may be cases in which the separate, additional step of cementing the periphery of the insole to the functional layer and the use of a waterproof insole are not desired.
EP 0 286 853 A discloses a process for sealing the lasting allowance of a shoe upper provided with a waterproof, water-vapour permeable functional layer in which an inner border region of the lasting allowance is kept uncemented during the cement-lasting and an injection mould with a sealing lip rising up towards the lasting allowance is placed against the underside of the lasting allowance after the lasting operation. In this case, the sealing lip essentially follows the contour of the insole border and is offset slightly towards the middle of the insole with respect to the outer peripheral contour of the outsole to be applied later. A sealing material is injected into the space inside the sealing lip and surrounds the border region of the upper provided with the functional layer, left uncemented during cement-lasting, and consequently seals the said region. Although this sealing process has proved to be very successful, it requires an injection mould and an injection machine of the type mentioned.
It is known from EP 0 595 941 B to seal the lasting allowance in a shoe with an upper which has a waterproof layer and is lasted around an insole in such a way that the border of the upper region to be lasted is embedded in a waterproof material, which may be polyurethane (PU), before the lasting operation. This sealing method has also proved to be very successful, but requires the additional process step of embedding the border of the lasting allowance.